Drop the Utils module

lib/draper.rb

@@ -1,7 +1,6 @@
 require 'action_view'
 
 require 'draper/version'
-require 'draper/utils'
 require 'draper/system'
 require 'draper/active_model_support'
 require 'draper/view_helpers'

lib/draper/decorator.rb

@@ -25,13 +25,9 @@ class Decorator
     def initialize(input, options = {})
       input.to_a if input.respond_to?(:to_a) # forces evaluation of a lazy query from AR
       self.class.model_class = input.class if model_class.nil?
-      @model = input
-      if input.instance_of?(self.class)
-        @model = input.model
-      elsif Utils.decorators_of(input).include?(self.class)
-        warn "Reapplying #{self.class} decorator to target that is already decorated with it. Call stack:\n#{caller(1).join "\n"}"
-      end
+      self.model = input
       self.options = options
+      handle_multiple_decoration if input.is_a?(Draper::Decorator)
     end
 
     # Proxies to the class specified by `decorates` to automatically
@@ -176,6 +172,21 @@ def self.last(options = {})
       decorate(model_class.last, options)
     end
 
+    # Get the chain of decorators applied to the object.
+    #
+    # @return [Array] list of decorator classes
+    def applied_decorators
+      chain = model.respond_to?(:applied_decorators) ? model.applied_decorators : []
+      chain << self.class
+    end
+
+    # Checks if a given decorator has been applied.
+    #
+    # @param [Class] decorator_class
+    def decorated_with?(decorator_class)
+      applied_decorators.include?(decorator_class)
+    end
+
     # Delegates == to the decorated models
     #
     # @return [Boolean] true if other's model == self's model
@@ -252,6 +263,14 @@ def allow?(method)
       self.class.security.allow?(method)
     end
 
+    def handle_multiple_decoration
+      if model.instance_of?(self.class)
+        self.model = model.model
+      elsif model.decorated_with?(self.class)
+        warn "Reapplying #{self.class} decorator to target that is already decorated with it. Call stack:\n#{caller(1).join("\n")}"
+      end
+    end
+
     def find_association_reflection(association)
       if model.class.respond_to?(:reflect_on_association)
         model.class.reflect_on_association(association)

spec/draper/decorator_spec.rb

@@ -268,6 +268,22 @@ class CustomDecorator < Draper::Decorator
     end
   end
 
+  describe "#applied_decorators" do
+    it "returns a list of decorators applied to a model" do
+      decorator = ProductDecorator.new(SpecificProductDecorator.new(Product.new))
+      decorator.applied_decorators.should == [SpecificProductDecorator, ProductDecorator]
+    end
+  end
+
+  describe "#decorated_with?" do
+    it "checks if a decorator has been applied to a model" do
+      decorator = ProductDecorator.new(SpecificProductDecorator.new(Product.new))
+      decorator.should be_decorated_with ProductDecorator
+      decorator.should be_decorated_with SpecificProductDecorator
+      decorator.should_not be_decorated_with WidgetDecorator
+    end
+  end
+
   context(".wrapped_object") do
     it "return the wrapped object" do
       subject.wrapped_object.should == source